diff --git a/libraries/AP_Compass/AP_Compass.cpp b/libraries/AP_Compass/AP_Compass.cpp
index b0f8dd01b8..da7c50ab9a 100644
--- a/libraries/AP_Compass/AP_Compass.cpp
+++ b/libraries/AP_Compass/AP_Compass.cpp
@@ -586,7 +586,7 @@ void Compass::_probe_external_i2c_compasses(void)
     bool both_i2c_external = (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXHAWK2);
     // external i2c bus
     FOREACH_I2C_EXTERNAL(i) {
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_HMC5843_I2C_ADDR),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(i, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                               true, ROTATION_ROLL_180),
                     AP_Compass_HMC5843::name, true);
     }
@@ -595,7 +595,7 @@ void Compass::_probe_external_i2c_compasses(void)
         AP_BoardConfig::get_board_type() != AP_BoardConfig::PX4_BOARD_AEROFC) {
         // internal i2c bus
         FOREACH_I2C_INTERNAL(i) {
-            ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_HMC5843_I2C_ADDR),
+            ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(i, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                                   both_i2c_external, both_i2c_external?ROTATION_ROLL_180:ROTATION_YAW_270),
                         AP_Compass_HMC5843::name, both_i2c_external);
         }
@@ -603,14 +603,14 @@ void Compass::_probe_external_i2c_compasses(void)
     
     //external i2c bus
     FOREACH_I2C_EXTERNAL(i) {
-        ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_QMC5883L_I2C_ADDR),
+        ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(i, HAL_COMPASS_QMC5883L_I2C_ADDR),
                                                                true, HAL_COMPASS_QMC5883L_ORIENTATION_EXTERNAL),
                     AP_Compass_QMC5883L::name, true);
     }
     
     //internal i2c bus
     FOREACH_I2C_INTERNAL(i) {
-        ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_QMC5883L_I2C_ADDR),
+        ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(i, HAL_COMPASS_QMC5883L_I2C_ADDR),
                                                                both_i2c_external,
                                                                both_i2c_external?HAL_COMPASS_QMC5883L_ORIENTATION_EXTERNAL:HAL_COMPASS_QMC5883L_ORIENTATION_INTERNAL),
                     AP_Compass_QMC5883L::name,both_i2c_external);
@@ -619,16 +619,14 @@ void Compass::_probe_external_i2c_compasses(void)
 #if !HAL_MINIMIZE_FEATURES
     // AK09916 on ICM20948
     FOREACH_I2C_EXTERNAL(i) {
-        ADD_BACKEND(DRIVER_ICM20948, AP_Compass_AK09916::probe_ICM20948(*this,
-                                                                        GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
+        ADD_BACKEND(DRIVER_ICM20948, AP_Compass_AK09916::probe_ICM20948(GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
                                                                         GET_I2C_DEVICE(i, HAL_COMPASS_ICM20948_I2C_ADDR),
                                                                         true, ROTATION_PITCH_180_YAW_90),
                     AP_Compass_AK09916::name, true);
     }
     
     FOREACH_I2C_INTERNAL(i) {
-        ADD_BACKEND(DRIVER_ICM20948, AP_Compass_AK09916::probe_ICM20948(*this,
-                                                                        GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
+        ADD_BACKEND(DRIVER_ICM20948, AP_Compass_AK09916::probe_ICM20948(GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
                                                                         GET_I2C_DEVICE(i, HAL_COMPASS_ICM20948_I2C_ADDR),
                                                                         both_i2c_external, ROTATION_PITCH_180_YAW_90),
                     AP_Compass_AK09916::name, true);
@@ -636,40 +634,40 @@ void Compass::_probe_external_i2c_compasses(void)
     
     // lis3mdl on bus 0 with default address
     FOREACH_I2C_INTERNAL(i) {
-        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR),
+        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR),
                                                               both_i2c_external, both_i2c_external?ROTATION_YAW_90:ROTATION_NONE),
                     AP_Compass_LIS3MDL::name, both_i2c_external);
     }
     
     // lis3mdl on bus 0 with alternate address
     FOREACH_I2C_INTERNAL(i) {
-        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR2),
+        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR2),
                                                               both_i2c_external, both_i2c_external?ROTATION_YAW_90:ROTATION_NONE),
                     AP_Compass_LIS3MDL::name, both_i2c_external);
     }
     
     // external lis3mdl on bus 1 with default address
     FOREACH_I2C_EXTERNAL(i) {
-        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR),
+        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR),
                                                               true, ROTATION_YAW_90),
                     AP_Compass_LIS3MDL::name, true);
     }
     
     // external lis3mdl on bus 1 with alternate address
     FOREACH_I2C_EXTERNAL(i) {
-        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR2),
+        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR2),
                                                               true, ROTATION_YAW_90),
                     AP_Compass_LIS3MDL::name, true);
     }
         
     // AK09916. This can be found twice, due to the ICM20948 i2c bus pass-thru, so we need to be careful to avoid that
     FOREACH_I2C_EXTERNAL(i) {
-        ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
+        ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
                                                               true, ROTATION_YAW_270),
                     AP_Compass_AK09916::name, true);
     }
     FOREACH_I2C_INTERNAL(i) {
-        ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
+        ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
                                                               both_i2c_external, both_i2c_external?ROTATION_YAW_270:ROTATION_NONE),
                     AP_Compass_AK09916::name, both_i2c_external);
     }
@@ -685,12 +683,12 @@ void Compass::_probe_external_i2c_compasses(void)
         }
 
         FOREACH_I2C_EXTERNAL(i) {
-            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
+            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
                                                                   true, default_rotation), AP_Compass_IST8310::name, true);
         }
         
         FOREACH_I2C_INTERNAL(i) {
-            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
+            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
                                                                   both_i2c_external, default_rotation), AP_Compass_IST8310::name, both_i2c_external);
         }
     }
@@ -703,7 +701,7 @@ void Compass::_probe_external_i2c_compasses(void)
 void Compass::_detect_backends(void)
 {
     if (_hil_mode) {
-        _add_backend(AP_Compass_HIL::detect(*this), nullptr, false);
+        _add_backend(AP_Compass_HIL::detect(), nullptr, false);
         return;
     }
 
@@ -715,7 +713,7 @@ void Compass::_detect_backends(void)
 #endif
     
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL
-    ADD_BACKEND(DRIVER_SITL, new AP_Compass_SITL(*this), nullptr, false);
+    ADD_BACKEND(DRIVER_SITL, new AP_Compass_SITL(), nullptr, false);
     return;
 #endif
 
@@ -729,7 +727,7 @@ void Compass::_detect_backends(void)
 #endif
     
 #if HAL_COMPASS_DEFAULT == HAL_COMPASS_HIL
-    ADD_BACKEND(DRIVER_SITL, AP_Compass_HIL::detect(*this), nullptr, false);
+    ADD_BACKEND(DRIVER_SITL, AP_Compass_HIL::detect(), nullptr, false);
 #elif AP_FEATURE_BOARD_DETECT
     switch (AP_BoardConfig::get_board_type()) {
     case AP_BoardConfig::PX4_BOARD_PX4V1:
@@ -752,17 +750,17 @@ void Compass::_detect_backends(void)
 
     case AP_BoardConfig::PX4_BOARD_PCNC1:
         ADD_BACKEND(DRIVER_BMM150,
-                    AP_Compass_BMM150::probe(*this, GET_I2C_DEVICE(0, 0x10)),
+                    AP_Compass_BMM150::probe(GET_I2C_DEVICE(0, 0x10)),
                     AP_Compass_BMM150::name, true);
         break;
     case AP_BoardConfig::VRX_BOARD_BRAIN54: {
         // external i2c bus
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(1, HAL_COMPASS_HMC5843_I2C_ADDR),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(1, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                               true, ROTATION_ROLL_180),
                     AP_Compass_HMC5843::name, true);
         }
         // internal i2c bus
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(0, HAL_COMPASS_HMC5843_I2C_ADDR),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(0, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                               false, ROTATION_YAW_270),
                     AP_Compass_HMC5843::name, false);
         break;
@@ -774,7 +772,7 @@ void Compass::_detect_backends(void)
     case AP_BoardConfig::VRX_BOARD_UBRAIN51:
     case AP_BoardConfig::VRX_BOARD_UBRAIN52: {
         // external i2c bus
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(1, HAL_COMPASS_HMC5843_I2C_ADDR),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(1, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                               true, ROTATION_ROLL_180),
                     AP_Compass_HMC5843::name, true);
         }
@@ -785,78 +783,78 @@ void Compass::_detect_backends(void)
     }
     switch (AP_BoardConfig::get_board_type()) {
     case AP_BoardConfig::PX4_BOARD_PIXHAWK:
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, hal.spi->get_device(HAL_COMPASS_HMC5843_NAME),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(hal.spi->get_device(HAL_COMPASS_HMC5843_NAME),
                                                               false, ROTATION_PITCH_180),
                     AP_Compass_HMC5843::name, false);
-        ADD_BACKEND(DRIVER_LSM303D, AP_Compass_LSM303D::probe(*this, hal.spi->get_device(HAL_INS_LSM9DS0_A_NAME)),
+        ADD_BACKEND(DRIVER_LSM303D, AP_Compass_LSM303D::probe(hal.spi->get_device(HAL_INS_LSM9DS0_A_NAME)),
                     AP_Compass_LSM303D::name, false);
         break;
 
     case AP_BoardConfig::PX4_BOARD_PIXHAWK2:
-        ADD_BACKEND(DRIVER_LSM303D, AP_Compass_LSM303D::probe(*this, hal.spi->get_device(HAL_INS_LSM9DS0_EXT_A_NAME), ROTATION_YAW_270),
+        ADD_BACKEND(DRIVER_LSM303D, AP_Compass_LSM303D::probe(hal.spi->get_device(HAL_INS_LSM9DS0_EXT_A_NAME), ROTATION_YAW_270),
                     AP_Compass_LSM303D::name, false);
         // we run the AK8963 only on the 2nd MPU9250, which leaves the
         // first MPU9250 to run without disturbance at high rate
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 1, ROTATION_YAW_270),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(1, ROTATION_YAW_270),
                     AP_Compass_AK8963::name, false);
         break;
 
     case AP_BoardConfig::PX4_BOARD_FMUV5:
         FOREACH_I2C_EXTERNAL(i) {
-            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
+            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
                                                                   true, ROTATION_ROLL_180_YAW_90), AP_Compass_IST8310::name, true);
         }
         FOREACH_I2C_INTERNAL(i) {
-            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
+            ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(i, HAL_COMPASS_IST8310_I2C_ADDR),
                                                                   false, ROTATION_ROLL_180_YAW_90), AP_Compass_IST8310::name, false);
         }
         break;
         
     case AP_BoardConfig::PX4_BOARD_SP01:
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 1, ROTATION_NONE),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(1, ROTATION_NONE),
                     AP_Compass_AK8963::name, false);
         break;
         
     case AP_BoardConfig::PX4_BOARD_PIXRACER:
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, hal.spi->get_device(HAL_COMPASS_HMC5843_NAME),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(hal.spi->get_device(HAL_COMPASS_HMC5843_NAME),
                                                               false, ROTATION_PITCH_180),
                     AP_Compass_HMC5843::name, false);
         // R15 has LIS3MDL on spi bus instead of HMC; same CS pin
-        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, hal.spi->get_device(HAL_COMPASS_LIS3MDL_NAME),
+        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(hal.spi->get_device(HAL_COMPASS_LIS3MDL_NAME),
                                                               false, ROTATION_NONE),
                     AP_Compass_LIS3MDL::name, false);
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0, ROTATION_ROLL_180_YAW_90),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0, ROTATION_ROLL_180_YAW_90),
                     AP_Compass_AK8963::name, false);
         break;
 
     case AP_BoardConfig::PX4_BOARD_PIXHAWK_PRO:
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0, ROTATION_ROLL_180_YAW_90),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0, ROTATION_ROLL_180_YAW_90),
                     AP_Compass_AK8963::name, false);
-        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, hal.spi->get_device(HAL_COMPASS_LIS3MDL_NAME),
+        ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(hal.spi->get_device(HAL_COMPASS_LIS3MDL_NAME),
                                                               false, ROTATION_NONE),
                     AP_Compass_LIS3MDL::name, false);
         break;
 
     case AP_BoardConfig::PX4_BOARD_PHMINI:
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0, ROTATION_ROLL_180),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0, ROTATION_ROLL_180),
                     AP_Compass_AK8963::name, false);
         break;
 
     case AP_BoardConfig::PX4_BOARD_AUAV21:
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0, ROTATION_ROLL_180_YAW_90),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0, ROTATION_ROLL_180_YAW_90),
                     AP_Compass_AK8963::name, false);
         break;
         
     case AP_BoardConfig::PX4_BOARD_PH2SLIM:
-        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0, ROTATION_YAW_270),
+        ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0, ROTATION_YAW_270),
                     AP_Compass_AK8963::name, false);
         break;
 
     case AP_BoardConfig::PX4_BOARD_MINDPXV2:
-        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(0, HAL_COMPASS_HMC5843_I2C_ADDR),
+        ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(0, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                               false, ROTATION_YAW_90),
                     AP_Compass_HMC5843::name, false);
-        ADD_BACKEND(DRIVER_LSM303D, AP_Compass_LSM303D::probe(*this, hal.spi->get_device(HAL_INS_LSM9DS0_A_NAME), ROTATION_PITCH_180_YAW_270),
+        ADD_BACKEND(DRIVER_LSM303D, AP_Compass_LSM303D::probe(hal.spi->get_device(HAL_INS_LSM9DS0_A_NAME), ROTATION_PITCH_180_YAW_270),
                     AP_Compass_LSM303D::name, false);
         break;
         
@@ -865,108 +863,108 @@ void Compass::_detect_backends(void)
     }
 
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_BH
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR)),
                 AP_Compass_HMC5843::name, false);
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0), AP_Compass_AK8963::name, false);
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0), AP_Compass_AK8963::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_BBBMINI
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 1),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(1),
                 AP_Compass_AK8963::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_NAVIO2
-    ADD_BACKEND(DRIVER_LSM9DS1, AP_Compass_LSM9DS1::probe(*this, hal.spi->get_device("lsm9ds1_m"), ROTATION_ROLL_180),
+    ADD_BACKEND(DRIVER_LSM9DS1, AP_Compass_LSM9DS1::probe(hal.spi->get_device("lsm9ds1_m"), ROTATION_ROLL_180),
                 AP_Compass_LSM9DS1::name, false);
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_NAVIO
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_OCPOC_ZYNQ
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR)),
                 AP_Compass_HMC5843::name, true);
-    ADD_BACKEND(DRIVER_AK8963,AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963,AP_Compass_AK8963::probe_mpu9250(0),
                  AP_Compass_AK8963::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_EDGE
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_PXF || \
       CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ERLEBRAIN2 || \
       CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_PXFMINI
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_BLUE
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, GET_I2C_DEVICE(HAL_COMPASS_AK8963_I2C_BUS, HAL_COMPASS_AK8963_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(GET_I2C_DEVICE(HAL_COMPASS_AK8963_I2C_BUS, HAL_COMPASS_AK8963_I2C_ADDR)),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                  AP_Compass_HMC5843::name, true);
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_POCKET
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_AK8963_MPU9250
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_HMC5843
 #ifndef HAL_COMPASS_HMC5843_ROTATION
 # define HAL_COMPASS_HMC5843_ROTATION ROTATION_NONE
 #endif
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                           false, HAL_COMPASS_HMC5843_ROTATION),
                 AP_Compass_HMC5843::name, false);
  #if defined(HAL_COMPASS_HMC5843_I2C_EXT_BUS) && CONFIG_HAL_BOARD == HAL_BOARD_F4LIGHT
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_EXT_BUS, HAL_COMPASS_HMC5843_I2C_ADDR),true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_EXT_BUS, HAL_COMPASS_HMC5843_I2C_ADDR),true),
                  AP_Compass_HMC5843::name, true);
  #endif
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_HMC5843_MPU6000
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe_mpu6000(*this),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe_mpu6000(),
                 AP_Compass_HMC5843::name, false);
 #elif  HAL_COMPASS_DEFAULT == HAL_COMPASS_AK8963_I2C
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_AK8963_I2C_BUS, HAL_COMPASS_AK8963_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe(GET_I2C_DEVICE(HAL_COMPASS_AK8963_I2C_BUS, HAL_COMPASS_AK8963_I2C_ADDR)),
                 AP_Compass_AK8963::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_AK8963_MPU9250_I2C
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, GET_I2C_DEVICE(HAL_COMPASS_AK8963_I2C_BUS, HAL_COMPASS_AK8963_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(GET_I2C_DEVICE(HAL_COMPASS_AK8963_I2C_BUS, HAL_COMPASS_AK8963_I2C_ADDR)),
                 AP_Compass_AK8963::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_AERO
-    ADD_BACKEND(DRIVER_BMM150, AP_Compass_BMM150::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_BMM150_I2C_BUS, HAL_COMPASS_BMM150_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_BMM150, AP_Compass_BMM150::probe(GET_I2C_DEVICE(HAL_COMPASS_BMM150_I2C_BUS, HAL_COMPASS_BMM150_I2C_ADDR)),
                 AP_Compass_BMM150::name, false);
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR), true),
                 AP_Compass_HMC5843::name, true);
-    ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_IST8310_I2C_BUS, HAL_COMPASS_IST8310_I2C_ADDR),
+    ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(HAL_COMPASS_IST8310_I2C_BUS, HAL_COMPASS_IST8310_I2C_ADDR),
                                                           true, ROTATION_PITCH_180_YAW_90), AP_Compass_IST8310::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_LIS3MDL
-    ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, hal.spi->get_device(HAL_COMPASS_LIS3MDL_NAME), false, ROTATION_ROLL_180_YAW_90),
+    ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(hal.spi->get_device(HAL_COMPASS_LIS3MDL_NAME), false, ROTATION_ROLL_180_YAW_90),
                 AP_Compass_LIS3MDL::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_MAG3110                
-    ADD_BACKEND(DRIVER_MAG3110, AP_Compass_MAG3110::probe(*this, GET_I2C_DEVICE(HAL_MAG3110_I2C_BUS, HAL_MAG3110_I2C_ADDR), ROTATION_NONE),
+    ADD_BACKEND(DRIVER_MAG3110, AP_Compass_MAG3110::probe(GET_I2C_DEVICE(HAL_MAG3110_I2C_BUS, HAL_MAG3110_I2C_ADDR), ROTATION_NONE),
                 AP_Compass_MAG3110::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_IST8310
-    ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_IST8310_I2C_BUS, HAL_COMPASS_IST8310_I2C_ADDR),
+    ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(HAL_COMPASS_IST8310_I2C_BUS, HAL_COMPASS_IST8310_I2C_ADDR),
                                                            true, ROTATION_PITCH_180_YAW_90), AP_Compass_IST8310::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_QMC5883L
-    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(*this, GET_I2C_DEVICE(1, HAL_COMPASS_QMC5883L_I2C_ADDR),
+    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(1, HAL_COMPASS_QMC5883L_I2C_ADDR),
                                                            true, HAL_COMPASS_QMC5883L_ORIENTATION_EXTERNAL),
                 AP_Compass_QMC5883L::name, true);
-    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(*this, GET_I2C_DEVICE(0, HAL_COMPASS_QMC5883L_I2C_ADDR),
+    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(0, HAL_COMPASS_QMC5883L_I2C_ADDR),
                                                            false, HAL_COMPASS_QMC5883L_ORIENTATION_INTERNAL),
                 AP_Compass_QMC5883L::name, false);
 #elif CONFIG_HAL_BOARD == HAL_BOARD_LINUX && CONFIG_HAL_BOARD_SUBTYPE != HAL_BOARD_SUBTYPE_LINUX_NONE
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR)),
                 AP_Compass_HMC5843::name, false);
-    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(*this, 0),
+    ADD_BACKEND(DRIVER_AK8963, AP_Compass_AK8963::probe_mpu9250(0),
                 AP_Compass_AK8963::name, false);
-    ADD_BACKEND(DRIVER_LSM9DS1, AP_Compass_LSM9DS1::probe(*this, hal.spi->get_device("lsm9ds1_m")),
+    ADD_BACKEND(DRIVER_LSM9DS1, AP_Compass_LSM9DS1::probe(hal.spi->get_device("lsm9ds1_m")),
                 AP_Compass_LSM9DS1::name, false);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_BMM150_I2C
-    ADD_BACKEND(DRIVER_BMM150, AP_Compass_BMM150::probe(*this, GET_I2C_DEVICE(HAL_COMPASS_BMM150_I2C_BUS, HAL_COMPASS_BMM150_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_BMM150, AP_Compass_BMM150::probe(GET_I2C_DEVICE(HAL_COMPASS_BMM150_I2C_BUS, HAL_COMPASS_BMM150_I2C_ADDR)),
                 AP_Compass_BMM150::name, true);
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_NONE
     // no compass
@@ -977,50 +975,50 @@ void Compass::_detect_backends(void)
 
 #if defined(BOARD_I2C_BUS_EXT) && CONFIG_HAL_BOARD == HAL_BOARD_F4LIGHT
 // autodetect external i2c bus
-    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_QMC5883L_I2C_ADDR),
+    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_QMC5883L_I2C_ADDR),
                                                                true,ROTATION_NONE),
                AP_Compass_QMC5883L::name, true);
 
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_HMC5843_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_HMC5843_I2C_ADDR)),
                 AP_Compass_HMC5843::name, true);
 
 
     // lis3mdl
-    ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_LIS3MDL_I2C_ADDR),
+    ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_LIS3MDL_I2C_ADDR),
                                                           true, ROTATION_NONE),
                 AP_Compass_LIS3MDL::name, true);
         
     // AK09916
-    ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_AK09916_I2C_ADDR),
+    ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_AK09916_I2C_ADDR),
                                                           true, ROTATION_NONE),
                 AP_Compass_AK09916::name, true);
 
-    ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_IST8310_I2C_ADDR),
+    ADD_BACKEND(DRIVER_IST8310, AP_Compass_IST8310::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_IST8310_I2C_ADDR),
                                                           ROTATION_NONE), 
                 AP_Compass_IST8310::name, true);
 
  #ifdef HAL_COMPASS_BMM150_I2C_ADDR
-    ADD_BACKEND(DRIVER_BMM150, AP_Compass_BMM150::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_BMM150_I2C_ADDR)),
+    ADD_BACKEND(DRIVER_BMM150, AP_Compass_BMM150::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_BMM150_I2C_ADDR)),
                 AP_Compass_BMM150::name, true);
  #endif
 
-    ADD_BACKEND(DRIVER_MAG3110, AP_Compass_MAG3110::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_MAG3110_I2C_ADDR), ROTATION_NONE),
+    ADD_BACKEND(DRIVER_MAG3110, AP_Compass_MAG3110::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_MAG3110_I2C_ADDR), ROTATION_NONE),
                 AP_Compass_MAG3110::name, true);
 
-    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(*this, GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_QMC5883L_I2C_ADDR), ROTATION_NONE),
+    ADD_BACKEND(DRIVER_QMC5883, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(BOARD_I2C_BUS_EXT, HAL_COMPASS_QMC5883L_I2C_ADDR), ROTATION_NONE),
                        AP_Compass_QMC5883L::name, true);
 #endif
 
 /* for chibios external board coniguration */
 #ifdef HAL_EXT_COMPASS_HMC5843_I2C_BUS
-    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(*this, GET_I2C_DEVICE(HAL_EXT_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR),
+    ADD_BACKEND(DRIVER_HMC5883, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(HAL_EXT_COMPASS_HMC5843_I2C_BUS, HAL_COMPASS_HMC5843_I2C_ADDR),
                                                           true, ROTATION_ROLL_180),
                 AP_Compass_HMC5843::name, true);
 #endif
 
 #if HAL_WITH_UAVCAN
     for (uint8_t i = 0; i < COMPASS_MAX_BACKEND; i++) {
-        ADD_BACKEND(DRIVER_UAVCAN, AP_Compass_UAVCAN::probe(*this), "UAVCAN", true);
+        ADD_BACKEND(DRIVER_UAVCAN, AP_Compass_UAVCAN::probe(), "UAVCAN", true);
     }
 #endif
 
diff --git a/libraries/AP_Compass/AP_Compass_AK09916.cpp b/libraries/AP_Compass/AP_Compass_AK09916.cpp
index 6004f6bf28..7efe4ddb17 100644
--- a/libraries/AP_Compass/AP_Compass_AK09916.cpp
+++ b/libraries/AP_Compass/AP_Compass_AK09916.cpp
@@ -48,15 +48,14 @@ extern const AP_HAL::HAL &hal;
 /*
   probe for AK09916 directly on I2C
  */
-AP_Compass_Backend *AP_Compass_AK09916::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+AP_Compass_Backend *AP_Compass_AK09916::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                               bool force_external,
                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_AK09916 *sensor = new AP_Compass_AK09916(compass, std::move(dev), nullptr,
+    AP_Compass_AK09916 *sensor = new AP_Compass_AK09916(std::move(dev), nullptr,
                                                         force_external,
                                                         rotation, AK09916_I2C);
     if (!sensor || !sensor->init()) {
@@ -71,8 +70,7 @@ AP_Compass_Backend *AP_Compass_AK09916::probe(Compass &compass,
 /*
   probe for AK09916 connected via an ICM20948
  */
-AP_Compass_Backend *AP_Compass_AK09916::probe_ICM20948(Compass &compass,
-                                                       AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+AP_Compass_Backend *AP_Compass_AK09916::probe_ICM20948(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                                        AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev_icm,
                                                        bool force_external,
                                                        enum Rotation rotation)
@@ -80,7 +78,7 @@ AP_Compass_Backend *AP_Compass_AK09916::probe_ICM20948(Compass &compass,
     if (!dev || !dev_icm) {
         return nullptr;
     }
-    AP_Compass_AK09916 *sensor = new AP_Compass_AK09916(compass, std::move(dev), std::move(dev_icm),
+    AP_Compass_AK09916 *sensor = new AP_Compass_AK09916(std::move(dev), std::move(dev_icm),
                                                         force_external,
                                                         rotation, AK09916_ICM20948_I2C);
     if (!sensor || !sensor->init()) {
@@ -91,14 +89,12 @@ AP_Compass_Backend *AP_Compass_AK09916::probe_ICM20948(Compass &compass,
     return sensor;
 }
 
-AP_Compass_AK09916::AP_Compass_AK09916(Compass &compass,
-                                       AP_HAL::OwnPtr<AP_HAL::Device> _dev,
+AP_Compass_AK09916::AP_Compass_AK09916(AP_HAL::OwnPtr<AP_HAL::Device> _dev,
                                        AP_HAL::OwnPtr<AP_HAL::Device> _dev_icm,
                                        bool _force_external,
                                        enum Rotation _rotation,
                                        enum bus_type _bus_type)
-    : AP_Compass_Backend(compass)
-    , bus_type(_bus_type)
+    : bus_type(_bus_type)
     , dev(std::move(_dev))
     , dev_icm(std::move(_dev_icm))
     , force_external(_force_external)
diff --git a/libraries/AP_Compass/AP_Compass_AK09916.h b/libraries/AP_Compass/AP_Compass_AK09916.h
index 8cdcc93735..0656949582 100644
--- a/libraries/AP_Compass/AP_Compass_AK09916.h
+++ b/libraries/AP_Compass/AP_Compass_AK09916.h
@@ -34,14 +34,12 @@
 class AP_Compass_AK09916 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                      bool force_external = false,
                                      enum Rotation rotation = ROTATION_NONE);
 
     // separate probe function for when behind a ICM20948 IMU
-    static AP_Compass_Backend *probe_ICM20948(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe_ICM20948(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                               AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev_icm,
                                               bool force_external = false,
                                               enum Rotation rotation = ROTATION_NONE);
@@ -56,8 +54,7 @@ private:
         AK09916_ICM20948_I2C,
     } bus_type;
     
-    AP_Compass_AK09916(Compass &compass,
-                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    AP_Compass_AK09916(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                        AP_HAL::OwnPtr<AP_HAL::Device> dev_icm,
                        bool force_external,
                        enum Rotation rotation,
diff --git a/libraries/AP_Compass/AP_Compass_AK8963.cpp b/libraries/AP_Compass/AP_Compass_AK8963.cpp
index 49f7e6d81a..c9267e2fab 100644
--- a/libraries/AP_Compass/AP_Compass_AK8963.cpp
+++ b/libraries/AP_Compass/AP_Compass_AK8963.cpp
@@ -52,10 +52,9 @@ struct PACKED sample_regs {
 
 extern const AP_HAL::HAL &hal;
 
-AP_Compass_AK8963::AP_Compass_AK8963(Compass &compass, AP_AK8963_BusDriver *bus,
+AP_Compass_AK8963::AP_Compass_AK8963(AP_AK8963_BusDriver *bus,
                                      enum Rotation rotation)
-    : AP_Compass_Backend(compass)
-    , _bus(bus)
+    : _bus(bus)
     , _rotation(rotation)
 {
 }
@@ -65,8 +64,7 @@ AP_Compass_AK8963::~AP_Compass_AK8963()
     delete _bus;
 }
 
-AP_Compass_Backend *AP_Compass_AK8963::probe(Compass &compass,
-                                             AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+AP_Compass_Backend *AP_Compass_AK8963::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                              enum Rotation rotation)
 {
     if (!dev) {
@@ -77,7 +75,7 @@ AP_Compass_Backend *AP_Compass_AK8963::probe(Compass &compass,
         return nullptr;
     }
 
-    AP_Compass_AK8963 *sensor = new AP_Compass_AK8963(compass, bus, rotation);
+    AP_Compass_AK8963 *sensor = new AP_Compass_AK8963(bus, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -86,8 +84,7 @@ AP_Compass_Backend *AP_Compass_AK8963::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(Compass &compass,
-                                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                                      enum Rotation rotation)
 {
     if (!dev) {
@@ -98,10 +95,10 @@ AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(Compass &compass,
     /* Allow MPU9250 to shortcut auxiliary bus and host bus */
     ins.detect_backends();
 
-    return probe(compass, std::move(dev), rotation);
+    return probe(std::move(dev), rotation);
 }
 
-AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(Compass &compass, uint8_t mpu9250_instance,
+AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(uint8_t mpu9250_instance,
                                                      enum Rotation rotation)
 {
     AP_InertialSensor &ins = *AP_InertialSensor::get_instance();
@@ -112,7 +109,7 @@ AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(Compass &compass, uint8_t m
         return nullptr;
     }
 
-    AP_Compass_AK8963 *sensor = new AP_Compass_AK8963(compass, bus, rotation);
+    AP_Compass_AK8963 *sensor = new AP_Compass_AK8963(bus, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
diff --git a/libraries/AP_Compass/AP_Compass_AK8963.h b/libraries/AP_Compass/AP_Compass_AK8963.h
index eb2d70e681..70d4460cf1 100644
--- a/libraries/AP_Compass/AP_Compass_AK8963.h
+++ b/libraries/AP_Compass/AP_Compass_AK8963.h
@@ -18,17 +18,15 @@ class AP_Compass_AK8963 : public AP_Compass_Backend
 {
 public:
     /* Probe for AK8963 standalone on I2C bus */
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                      enum Rotation rotation = ROTATION_NONE);
 
     /* Probe for AK8963 on auxiliary bus of MPU9250, connected through I2C */
-    static AP_Compass_Backend *probe_mpu9250(Compass &compass,
-                                             AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe_mpu9250(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                              enum Rotation rotation = ROTATION_NONE);
 
     /* Probe for AK8963 on auxiliary bus of MPU9250, connected through SPI */
-    static AP_Compass_Backend *probe_mpu9250(Compass &compass, uint8_t mpu9250_instance,
+    static AP_Compass_Backend *probe_mpu9250(uint8_t mpu9250_instance,
                                              enum Rotation rotation = ROTATION_NONE);
 
     static constexpr const char *name = "AK8963";
@@ -38,7 +36,7 @@ public:
     void read() override;
 
 private:
-    AP_Compass_AK8963(Compass &compass, AP_AK8963_BusDriver *bus,
+    AP_Compass_AK8963(AP_AK8963_BusDriver *bus,
                       enum Rotation rotation = ROTATION_NONE);
 
     bool init();
diff --git a/libraries/AP_Compass/AP_Compass_BMM150.cpp b/libraries/AP_Compass/AP_Compass_BMM150.cpp
index e31b5426ff..113bff3dc1 100644
--- a/libraries/AP_Compass/AP_Compass_BMM150.cpp
+++ b/libraries/AP_Compass/AP_Compass_BMM150.cpp
@@ -63,13 +63,12 @@
 
 extern const AP_HAL::HAL &hal;
 
-AP_Compass_Backend *AP_Compass_BMM150::probe(Compass &compass,
-                                             AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
+AP_Compass_Backend *AP_Compass_BMM150::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_BMM150 *sensor = new AP_Compass_BMM150(compass, std::move(dev));
+    AP_Compass_BMM150 *sensor = new AP_Compass_BMM150(std::move(dev));
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -78,10 +77,8 @@ AP_Compass_Backend *AP_Compass_BMM150::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_BMM150::AP_Compass_BMM150(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::Device> dev)
-    : AP_Compass_Backend(compass)
-    , _dev(std::move(dev))
+AP_Compass_BMM150::AP_Compass_BMM150(AP_HAL::OwnPtr<AP_HAL::Device> dev)
+    : _dev(std::move(dev))
 {
 }
 
diff --git a/libraries/AP_Compass/AP_Compass_BMM150.h b/libraries/AP_Compass/AP_Compass_BMM150.h
index 37eb95d250..fefe5e4635 100644
--- a/libraries/AP_Compass/AP_Compass_BMM150.h
+++ b/libraries/AP_Compass/AP_Compass_BMM150.h
@@ -27,15 +27,14 @@
 class AP_Compass_BMM150 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev);
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev);
 
     void read() override;
 
     static constexpr const char *name = "BMM150";
 
 private:
-    AP_Compass_BMM150(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev);
+    AP_Compass_BMM150(AP_HAL::OwnPtr<AP_HAL::Device> dev);
 
     /**
      * Device periodic callback to read data from the sensor.
diff --git a/libraries/AP_Compass/AP_Compass_Backend.cpp b/libraries/AP_Compass/AP_Compass_Backend.cpp
index 83eb1e46f2..d938ab176b 100644
--- a/libraries/AP_Compass/AP_Compass_Backend.cpp
+++ b/libraries/AP_Compass/AP_Compass_Backend.cpp
@@ -6,10 +6,10 @@
 
 extern const AP_HAL::HAL& hal;
 
-AP_Compass_Backend::AP_Compass_Backend(Compass &compass) :
-    _compass(compass)
+AP_Compass_Backend::AP_Compass_Backend()
+    : _compass(AP::compass())
 {
-    _sem = hal.util->new_semaphore();    
+    _sem = hal.util->new_semaphore();
 }
 
 void AP_Compass_Backend::rotate_field(Vector3f &mag, uint8_t instance)
diff --git a/libraries/AP_Compass/AP_Compass_Backend.h b/libraries/AP_Compass/AP_Compass_Backend.h
index 653fbacb6a..24bb60adae 100644
--- a/libraries/AP_Compass/AP_Compass_Backend.h
+++ b/libraries/AP_Compass/AP_Compass_Backend.h
@@ -25,7 +25,7 @@ class Compass;  // forward declaration
 class AP_Compass_Backend
 {
 public:
-    AP_Compass_Backend(Compass &compass);
+    AP_Compass_Backend();
 
     // we declare a virtual destructor so that drivers can
     // override with a custom destructor if need be.
diff --git a/libraries/AP_Compass/AP_Compass_HIL.cpp b/libraries/AP_Compass/AP_Compass_HIL.cpp
index 188ed82ad7..284b2884ee 100644
--- a/libraries/AP_Compass/AP_Compass_HIL.cpp
+++ b/libraries/AP_Compass/AP_Compass_HIL.cpp
@@ -25,17 +25,16 @@
 extern const AP_HAL::HAL& hal;
 
 // constructor
-AP_Compass_HIL::AP_Compass_HIL(Compass &compass):
-    AP_Compass_Backend(compass)
+AP_Compass_HIL::AP_Compass_HIL()
 {
     memset(_compass_instance, 0, sizeof(_compass_instance));
     _compass._setup_earth_field();
 }
 
 // detect the sensor
-AP_Compass_Backend *AP_Compass_HIL::detect(Compass &compass)
+AP_Compass_Backend *AP_Compass_HIL::detect()
 {
-    AP_Compass_HIL *sensor = new AP_Compass_HIL(compass);
+    AP_Compass_HIL *sensor = new AP_Compass_HIL();
     if (sensor == nullptr) {
         return nullptr;
     }
diff --git a/libraries/AP_Compass/AP_Compass_HIL.h b/libraries/AP_Compass/AP_Compass_HIL.h
index 628eb88464..61981fed06 100644
--- a/libraries/AP_Compass/AP_Compass_HIL.h
+++ b/libraries/AP_Compass/AP_Compass_HIL.h
@@ -7,12 +7,12 @@
 class AP_Compass_HIL : public AP_Compass_Backend
 {
 public:
-    AP_Compass_HIL(Compass &compass);
+    AP_Compass_HIL();
     void read(void);
     bool init(void);
 
     // detect the sensor
-    static AP_Compass_Backend *detect(Compass &compass);
+    static AP_Compass_Backend *detect();
 
 private:
     uint8_t     _compass_instance[HIL_NUM_COMPASSES];
diff --git a/libraries/AP_Compass/AP_Compass_HMC5843.cpp b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
index bdeafdab9b..f5fc6b60f8 100644
--- a/libraries/AP_Compass/AP_Compass_HMC5843.cpp
+++ b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
@@ -94,10 +94,9 @@ extern const AP_HAL::HAL& hal;
 #define HMC5843_REG_ID_A 0x0A
 
 
-AP_Compass_HMC5843::AP_Compass_HMC5843(Compass &compass, AP_HMC5843_BusDriver *bus,
+AP_Compass_HMC5843::AP_Compass_HMC5843(AP_HMC5843_BusDriver *bus,
                                        bool force_external, enum Rotation rotation)
-    : AP_Compass_Backend(compass)
-    , _bus(bus)
+    : _bus(bus)
     , _rotation(rotation)
     , _force_external(force_external)
 {
@@ -108,8 +107,7 @@ AP_Compass_HMC5843::~AP_Compass_HMC5843()
     delete _bus;
 }
 
-AP_Compass_Backend *AP_Compass_HMC5843::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_Backend *AP_Compass_HMC5843::probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                               bool force_external,
                                               enum Rotation rotation)
 {
@@ -121,7 +119,7 @@ AP_Compass_Backend *AP_Compass_HMC5843::probe(Compass &compass,
         return nullptr;
     }
 
-    AP_Compass_HMC5843 *sensor = new AP_Compass_HMC5843(compass, bus, force_external, rotation);
+    AP_Compass_HMC5843 *sensor = new AP_Compass_HMC5843(bus, force_external, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -130,7 +128,7 @@ AP_Compass_Backend *AP_Compass_HMC5843::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_Backend *AP_Compass_HMC5843::probe_mpu6000(Compass &compass, enum Rotation rotation)
+AP_Compass_Backend *AP_Compass_HMC5843::probe_mpu6000(enum Rotation rotation)
 {
     AP_InertialSensor &ins = *AP_InertialSensor::get_instance();
 
@@ -141,7 +139,7 @@ AP_Compass_Backend *AP_Compass_HMC5843::probe_mpu6000(Compass &compass, enum Rot
         return nullptr;
     }
 
-    AP_Compass_HMC5843 *sensor = new AP_Compass_HMC5843(compass, bus, false, rotation);
+    AP_Compass_HMC5843 *sensor = new AP_Compass_HMC5843(bus, false, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
diff --git a/libraries/AP_Compass/AP_Compass_HMC5843.h b/libraries/AP_Compass/AP_Compass_HMC5843.h
index 11c4cca793..0dbbe65a09 100644
--- a/libraries/AP_Compass/AP_Compass_HMC5843.h
+++ b/libraries/AP_Compass/AP_Compass_HMC5843.h
@@ -16,13 +16,11 @@ class AP_HMC5843_BusDriver;
 class AP_Compass_HMC5843 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                      bool force_external = false,
                                      enum Rotation rotation = ROTATION_NONE);
 
-    static AP_Compass_Backend *probe_mpu6000(Compass &compass,
-                                             enum Rotation rotation = ROTATION_NONE);
+    static AP_Compass_Backend *probe_mpu6000(enum Rotation rotation = ROTATION_NONE);
 
     static constexpr const char *name = "HMC5843";
 
@@ -31,7 +29,7 @@ public:
     void read() override;
 
 private:
-    AP_Compass_HMC5843(Compass &compass, AP_HMC5843_BusDriver *bus,
+    AP_Compass_HMC5843(AP_HMC5843_BusDriver *bus,
                        bool force_external, enum Rotation rotation);
 
     bool init();
diff --git a/libraries/AP_Compass/AP_Compass_IST8310.cpp b/libraries/AP_Compass/AP_Compass_IST8310.cpp
index f679be2662..e11b99a4d1 100644
--- a/libraries/AP_Compass/AP_Compass_IST8310.cpp
+++ b/libraries/AP_Compass/AP_Compass_IST8310.cpp
@@ -75,8 +75,7 @@ static const int16_t IST8310_MIN_VAL_Z  = -IST8310_MAX_VAL_Z;
 
 extern const AP_HAL::HAL &hal;
 
-AP_Compass_Backend *AP_Compass_IST8310::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+AP_Compass_Backend *AP_Compass_IST8310::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                               bool force_external,
                                               enum Rotation rotation)
 {
@@ -84,7 +83,7 @@ AP_Compass_Backend *AP_Compass_IST8310::probe(Compass &compass,
         return nullptr;
     }
 
-    AP_Compass_IST8310 *sensor = new AP_Compass_IST8310(compass, std::move(dev), force_external, rotation);
+    AP_Compass_IST8310 *sensor = new AP_Compass_IST8310(std::move(dev), force_external, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -93,12 +92,10 @@ AP_Compass_Backend *AP_Compass_IST8310::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_IST8310::AP_Compass_IST8310(Compass &compass,
-                                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_IST8310::AP_Compass_IST8310(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                        bool force_external,
                                        enum Rotation rotation)
-    : AP_Compass_Backend(compass)
-    , _dev(std::move(dev))
+    : _dev(std::move(dev))
     , _rotation(rotation)
     , _force_external(force_external)
 {
diff --git a/libraries/AP_Compass/AP_Compass_IST8310.h b/libraries/AP_Compass/AP_Compass_IST8310.h
index a466a1be5c..7a130e2b7e 100644
--- a/libraries/AP_Compass/AP_Compass_IST8310.h
+++ b/libraries/AP_Compass/AP_Compass_IST8310.h
@@ -31,8 +31,7 @@
 class AP_Compass_IST8310 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                      bool force_external = false,
                                      enum Rotation rotation = ROTATION_NONE);
 
@@ -41,8 +40,7 @@ public:
     static constexpr const char *name = "IST8310";
 
 private:
-    AP_Compass_IST8310(Compass &compass,
-                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    AP_Compass_IST8310(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                        bool force_external,
                        enum Rotation rotation);
 
diff --git a/libraries/AP_Compass/AP_Compass_LIS3MDL.cpp b/libraries/AP_Compass/AP_Compass_LIS3MDL.cpp
index c3442047d9..f4b2b6704d 100644
--- a/libraries/AP_Compass/AP_Compass_LIS3MDL.cpp
+++ b/libraries/AP_Compass/AP_Compass_LIS3MDL.cpp
@@ -48,15 +48,14 @@
 
 extern const AP_HAL::HAL &hal;
 
-AP_Compass_Backend *AP_Compass_LIS3MDL::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_Backend *AP_Compass_LIS3MDL::probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                               bool force_external,
                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_LIS3MDL *sensor = new AP_Compass_LIS3MDL(compass, std::move(dev), force_external, rotation);
+    AP_Compass_LIS3MDL *sensor = new AP_Compass_LIS3MDL(std::move(dev), force_external, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -65,12 +64,10 @@ AP_Compass_Backend *AP_Compass_LIS3MDL::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_LIS3MDL::AP_Compass_LIS3MDL(Compass &compass,
-                                       AP_HAL::OwnPtr<AP_HAL::Device> _dev,
+AP_Compass_LIS3MDL::AP_Compass_LIS3MDL(AP_HAL::OwnPtr<AP_HAL::Device> _dev,
                                        bool _force_external,
                                        enum Rotation _rotation)
-    : AP_Compass_Backend(compass)
-    , dev(std::move(_dev))
+    : dev(std::move(_dev))
     , force_external(_force_external)
     , rotation(_rotation)
 {
diff --git a/libraries/AP_Compass/AP_Compass_LIS3MDL.h b/libraries/AP_Compass/AP_Compass_LIS3MDL.h
index bb5b0f1249..f74a8bcb23 100644
--- a/libraries/AP_Compass/AP_Compass_LIS3MDL.h
+++ b/libraries/AP_Compass/AP_Compass_LIS3MDL.h
@@ -33,8 +33,7 @@
 class AP_Compass_LIS3MDL : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                      bool force_external = false,
                                      enum Rotation rotation = ROTATION_NONE);
 
@@ -43,7 +42,7 @@ public:
     static constexpr const char *name = "LIS3MDL";
 
 private:
-    AP_Compass_LIS3MDL(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    AP_Compass_LIS3MDL(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                        bool force_external,
                        enum Rotation rotation);
 
diff --git a/libraries/AP_Compass/AP_Compass_LSM303D.cpp b/libraries/AP_Compass/AP_Compass_LSM303D.cpp
index 94ff18f9a3..7d4b929fe6 100644
--- a/libraries/AP_Compass/AP_Compass_LSM303D.cpp
+++ b/libraries/AP_Compass/AP_Compass_LSM303D.cpp
@@ -150,20 +150,18 @@ extern const AP_HAL::HAL &hal;
 #define LSM303D_MAG_DEFAULT_RANGE_GA          2
 #define LSM303D_MAG_DEFAULT_RATE            100
 
-AP_Compass_LSM303D::AP_Compass_LSM303D(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev)
-    : AP_Compass_Backend(compass)
-    , _dev(std::move(dev))
+AP_Compass_LSM303D::AP_Compass_LSM303D(AP_HAL::OwnPtr<AP_HAL::Device> dev)
+    : _dev(std::move(dev))
 {
 }
 
-AP_Compass_Backend *AP_Compass_LSM303D::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_Backend *AP_Compass_LSM303D::probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_LSM303D *sensor = new AP_Compass_LSM303D(compass, std::move(dev));
+    AP_Compass_LSM303D *sensor = new AP_Compass_LSM303D(std::move(dev));
     if (!sensor || !sensor->init(rotation)) {
         delete sensor;
         return nullptr;
diff --git a/libraries/AP_Compass/AP_Compass_LSM303D.h b/libraries/AP_Compass/AP_Compass_LSM303D.h
index dcc263ba76..901ee6d06b 100644
--- a/libraries/AP_Compass/AP_Compass_LSM303D.h
+++ b/libraries/AP_Compass/AP_Compass_LSM303D.h
@@ -11,8 +11,7 @@
 class AP_Compass_LSM303D : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                      enum Rotation = ROTATION_NONE);
 
     static constexpr const char *name = "LSM303D";
@@ -22,7 +21,7 @@ public:
     virtual ~AP_Compass_LSM303D() { }
 
 private:
-    AP_Compass_LSM303D(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev);
+    AP_Compass_LSM303D(AP_HAL::OwnPtr<AP_HAL::Device> dev);
 
     bool init(enum Rotation rotation);
     uint8_t _register_read(uint8_t reg);
diff --git a/libraries/AP_Compass/AP_Compass_LSM9DS1.cpp b/libraries/AP_Compass/AP_Compass_LSM9DS1.cpp
index fbabb7bdba..431e09d9de 100644
--- a/libraries/AP_Compass/AP_Compass_LSM9DS1.cpp
+++ b/libraries/AP_Compass/AP_Compass_LSM9DS1.cpp
@@ -57,23 +57,20 @@ struct PACKED sample_regs {
 
 extern const AP_HAL::HAL &hal;
 
-AP_Compass_LSM9DS1::AP_Compass_LSM9DS1(Compass &compass,
-                                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_LSM9DS1::AP_Compass_LSM9DS1(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                        enum Rotation rotation)
-    : AP_Compass_Backend(compass)
-    , _dev(std::move(dev))
+    : _dev(std::move(dev))
     , _rotation(rotation)
 {
 }
 
-AP_Compass_Backend *AP_Compass_LSM9DS1::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_Backend *AP_Compass_LSM9DS1::probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_LSM9DS1 *sensor = new AP_Compass_LSM9DS1(compass, std::move(dev), rotation);
+    AP_Compass_LSM9DS1 *sensor = new AP_Compass_LSM9DS1(std::move(dev), rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
diff --git a/libraries/AP_Compass/AP_Compass_LSM9DS1.h b/libraries/AP_Compass/AP_Compass_LSM9DS1.h
index db860252f5..f2139eaecd 100644
--- a/libraries/AP_Compass/AP_Compass_LSM9DS1.h
+++ b/libraries/AP_Compass/AP_Compass_LSM9DS1.h
@@ -11,8 +11,7 @@
 class AP_Compass_LSM9DS1 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                      enum Rotation rotation = ROTATION_NONE);
 
     static constexpr const char *name = "LSM9DS1";
@@ -22,7 +21,7 @@ public:
     virtual ~AP_Compass_LSM9DS1() {}
 
 private:
-    AP_Compass_LSM9DS1(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    AP_Compass_LSM9DS1(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                        enum Rotation rotation = ROTATION_NONE);
     bool init();
     bool _check_id(void);
diff --git a/libraries/AP_Compass/AP_Compass_MAG3110.cpp b/libraries/AP_Compass/AP_Compass_MAG3110.cpp
index 41c287a72c..455c712bc0 100644
--- a/libraries/AP_Compass/AP_Compass_MAG3110.cpp
+++ b/libraries/AP_Compass/AP_Compass_MAG3110.cpp
@@ -80,20 +80,18 @@ RUS:
 
 
 
-AP_Compass_MAG3110::AP_Compass_MAG3110(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev)
-    : AP_Compass_Backend(compass)
-    , _dev(std::move(dev))
+AP_Compass_MAG3110::AP_Compass_MAG3110(AP_HAL::OwnPtr<AP_HAL::Device> dev)
+    : _dev(std::move(dev))
 {
 }
 
-AP_Compass_Backend *AP_Compass_MAG3110::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::Device> dev,
+AP_Compass_Backend *AP_Compass_MAG3110::probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_MAG3110 *sensor = new AP_Compass_MAG3110(compass, std::move(dev));
+    AP_Compass_MAG3110 *sensor = new AP_Compass_MAG3110(std::move(dev));
     if (!sensor || !sensor->init(rotation)) {
         delete sensor;
         return nullptr;
diff --git a/libraries/AP_Compass/AP_Compass_MAG3110.h b/libraries/AP_Compass/AP_Compass_MAG3110.h
index b5d6e86f17..dba9f5ff96 100644
--- a/libraries/AP_Compass/AP_Compass_MAG3110.h
+++ b/libraries/AP_Compass/AP_Compass_MAG3110.h
@@ -16,8 +16,7 @@
 class AP_Compass_MAG3110 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                      enum Rotation = ROTATION_NONE);
 
     static constexpr const char *name = "MAG3110";
@@ -27,7 +26,7 @@ public:
     ~AP_Compass_MAG3110() { }
 
 private:
-    AP_Compass_MAG3110(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev);
+    AP_Compass_MAG3110(AP_HAL::OwnPtr<AP_HAL::Device> dev);
 
     bool init(enum Rotation rotation);
 
diff --git a/libraries/AP_Compass/AP_Compass_MMC3416.cpp b/libraries/AP_Compass/AP_Compass_MMC3416.cpp
index e140977c3c..e6c7eed0fe 100644
--- a/libraries/AP_Compass/AP_Compass_MMC3416.cpp
+++ b/libraries/AP_Compass/AP_Compass_MMC3416.cpp
@@ -41,15 +41,14 @@ extern const AP_HAL::HAL &hal;
 // datasheet says 50ms min for refill
 #define MIN_DELAY_SET_RESET 50
 
-AP_Compass_Backend *AP_Compass_MMC3416::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+AP_Compass_Backend *AP_Compass_MMC3416::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                               bool force_external,
                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
-    AP_Compass_MMC3416 *sensor = new AP_Compass_MMC3416(compass, std::move(dev), force_external, rotation);
+    AP_Compass_MMC3416 *sensor = new AP_Compass_MMC3416(std::move(dev), force_external, rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -58,12 +57,10 @@ AP_Compass_Backend *AP_Compass_MMC3416::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_MMC3416::AP_Compass_MMC3416(Compass &compass,
-                                       AP_HAL::OwnPtr<AP_HAL::Device> _dev,
+AP_Compass_MMC3416::AP_Compass_MMC3416(AP_HAL::OwnPtr<AP_HAL::Device> _dev,
                                        bool _force_external,
                                        enum Rotation _rotation)
-    : AP_Compass_Backend(compass)
-    , dev(std::move(_dev))
+    : dev(std::move(_dev))
     , force_external(_force_external)
     , rotation(_rotation)
 {
diff --git a/libraries/AP_Compass/AP_Compass_MMC3416.h b/libraries/AP_Compass/AP_Compass_MMC3416.h
index 8c0b208971..453eb90fd3 100644
--- a/libraries/AP_Compass/AP_Compass_MMC3416.h
+++ b/libraries/AP_Compass/AP_Compass_MMC3416.h
@@ -29,8 +29,7 @@
 class AP_Compass_MMC3416 : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                      bool force_external = false,
                                      enum Rotation rotation = ROTATION_NONE);
 
@@ -39,7 +38,7 @@ public:
     static constexpr const char *name = "MMC3416";
 
 private:
-    AP_Compass_MMC3416(Compass &compass, AP_HAL::OwnPtr<AP_HAL::Device> dev,
+    AP_Compass_MMC3416(AP_HAL::OwnPtr<AP_HAL::Device> dev,
                        bool force_external,
                        enum Rotation rotation);
 
diff --git a/libraries/AP_Compass/AP_Compass_QMC5883L.cpp b/libraries/AP_Compass/AP_Compass_QMC5883L.cpp
index 16ab1e0c12..a0d89296c1 100644
--- a/libraries/AP_Compass/AP_Compass_QMC5883L.cpp
+++ b/libraries/AP_Compass/AP_Compass_QMC5883L.cpp
@@ -57,16 +57,15 @@
 
 extern const AP_HAL::HAL &hal;
 
-AP_Compass_Backend *AP_Compass_QMC5883L::probe(Compass &compass,
-                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
-											  bool force_external,
-											  enum Rotation rotation)
+AP_Compass_Backend *AP_Compass_QMC5883L::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+                                               bool force_external,
+                                               enum Rotation rotation)
 {
     if (!dev) {
         return nullptr;
     }
 
-    AP_Compass_QMC5883L *sensor = new AP_Compass_QMC5883L(compass, std::move(dev),force_external,rotation);
+    AP_Compass_QMC5883L *sensor = new AP_Compass_QMC5883L(std::move(dev),force_external,rotation);
     if (!sensor || !sensor->init()) {
         delete sensor;
         return nullptr;
@@ -75,12 +74,10 @@ AP_Compass_Backend *AP_Compass_QMC5883L::probe(Compass &compass,
     return sensor;
 }
 
-AP_Compass_QMC5883L::AP_Compass_QMC5883L(Compass &compass,
-                                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
-									   bool force_external,
-									   enum Rotation rotation)
-    : AP_Compass_Backend(compass)
-    , _dev(std::move(dev))
+AP_Compass_QMC5883L::AP_Compass_QMC5883L(AP_HAL::OwnPtr<AP_HAL::Device> dev,
+                                         bool force_external,
+                                         enum Rotation rotation)
+    : _dev(std::move(dev))
     , _rotation(rotation)
 	, _force_external(force_external)
 {
diff --git a/libraries/AP_Compass/AP_Compass_QMC5883L.h b/libraries/AP_Compass/AP_Compass_QMC5883L.h
index 4e94ae9d06..a4d24535aa 100644
--- a/libraries/AP_Compass/AP_Compass_QMC5883L.h
+++ b/libraries/AP_Compass/AP_Compass_QMC5883L.h
@@ -42,8 +42,7 @@
 class AP_Compass_QMC5883L : public AP_Compass_Backend
 {
 public:
-    static AP_Compass_Backend *probe(Compass &compass,
-                                     AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
+    static AP_Compass_Backend *probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
 									 bool force_external,
                                      enum Rotation rotation = ROTATION_NONE);
 
@@ -52,10 +51,9 @@ public:
     static constexpr const char *name = "QMC5883L";
 
 private:
-    AP_Compass_QMC5883L(Compass &compass,
-                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
-					   bool force_external,
-                       enum Rotation rotation);
+    AP_Compass_QMC5883L(AP_HAL::OwnPtr<AP_HAL::Device> dev,
+                        bool force_external,
+                        enum Rotation rotation);
 
     void _dump_registers();
     bool _check_whoami();
diff --git a/libraries/AP_Compass/AP_Compass_SITL.cpp b/libraries/AP_Compass/AP_Compass_SITL.cpp
index a063705173..524697c471 100644
--- a/libraries/AP_Compass/AP_Compass_SITL.cpp
+++ b/libraries/AP_Compass/AP_Compass_SITL.cpp
@@ -5,16 +5,15 @@
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL
 extern const AP_HAL::HAL& hal;
 
-AP_Compass_SITL::AP_Compass_SITL(Compass &compass):
+AP_Compass_SITL::AP_Compass_SITL():
     _sitl(AP::sitl()),
     _has_sample(false),
-    AP_Compass_Backend(compass)
 {
     if (_sitl != nullptr) {
         _compass._setup_earth_field();
         for (uint8_t i=0; i<SITL_NUM_COMPASSES; i++) {
             // default offsets to correct value
-            compass.set_offsets(i, _sitl->mag_ofs);
+            _compass.set_offsets(i, _sitl->mag_ofs);
             
             _compass_instance[i] = register_compass();
             set_dev_id(_compass_instance[i], AP_HAL::Device::make_bus_id(AP_HAL::Device::BUS_TYPE_SITL, i, 0, DEVTYPE_SITL));
diff --git a/libraries/AP_Compass/AP_Compass_SITL.h b/libraries/AP_Compass/AP_Compass_SITL.h
index e5e0c4c650..b11da3866d 100644
--- a/libraries/AP_Compass/AP_Compass_SITL.h
+++ b/libraries/AP_Compass/AP_Compass_SITL.h
@@ -13,7 +13,7 @@
 
 class AP_Compass_SITL : public AP_Compass_Backend {
 public:
-    AP_Compass_SITL(Compass &);
+    AP_Compass_SITL();
 
     void read(void);
 
diff --git a/libraries/AP_Compass/AP_Compass_UAVCAN.cpp b/libraries/AP_Compass/AP_Compass_UAVCAN.cpp
index b785cd7a16..6400f1f4c1 100644
--- a/libraries/AP_Compass/AP_Compass_UAVCAN.cpp
+++ b/libraries/AP_Compass/AP_Compass_UAVCAN.cpp
@@ -38,15 +38,12 @@ UC_REGISTRY_BINDER(Mag2Cb, uavcan::equipment::ahrs::MagneticFieldStrength2);
 AP_Compass_UAVCAN::DetectedModules AP_Compass_UAVCAN::_detected_modules[] = {0};
 AP_HAL::Semaphore* AP_Compass_UAVCAN::_sem_registry = nullptr;
 
-/*
-  constructor - registers instance at top Compass driver
- */
-AP_Compass_UAVCAN::AP_Compass_UAVCAN(Compass &compass, AP_UAVCAN* ap_uavcan, uint8_t node_id, uint8_t sensor_id):
-    AP_Compass_Backend(compass),
-    _ap_uavcan(ap_uavcan),
-    _node_id(node_id),
-    _sensor_id(sensor_id)
-{}
+AP_Compass_UAVCAN::AP_Compass_UAVCAN(AP_UAVCAN* ap_uavcan, uint8_t node_id, uint8_t sensor_id)
+    : _ap_uavcan(ap_uavcan)
+    , _node_id(node_id)
+    , _sensor_id(sensor_id)
+{
+}
 
 void AP_Compass_UAVCAN::subscribe_msgs(AP_UAVCAN* ap_uavcan)
 {
@@ -86,7 +83,7 @@ void AP_Compass_UAVCAN::give_registry()
     _sem_registry->give();
 }
 
-AP_Compass_Backend* AP_Compass_UAVCAN::probe(Compass& _frontend)
+AP_Compass_Backend* AP_Compass_UAVCAN::probe()
 {
     if (!take_registry()) {
         return nullptr;
@@ -95,7 +92,7 @@ AP_Compass_Backend* AP_Compass_UAVCAN::probe(Compass& _frontend)
     for (uint8_t i = 0; i < COMPASS_MAX_BACKEND; i++) {
         if (!_detected_modules[i].driver && _detected_modules[i].ap_uavcan) {
             // Register new Compass mode to a backend
-            driver = new AP_Compass_UAVCAN(_frontend, _detected_modules[i].ap_uavcan, _detected_modules[i].node_id, _detected_modules[i].sensor_id);
+            driver = new AP_Compass_UAVCAN(_detected_modules[i].ap_uavcan, _detected_modules[i].node_id, _detected_modules[i].sensor_id);
             if (driver) {
                 _detected_modules[i].driver = driver;
                 driver->init();
diff --git a/libraries/AP_Compass/AP_Compass_UAVCAN.h b/libraries/AP_Compass/AP_Compass_UAVCAN.h
index 1922967411..4cce04b0e1 100644
--- a/libraries/AP_Compass/AP_Compass_UAVCAN.h
+++ b/libraries/AP_Compass/AP_Compass_UAVCAN.h
@@ -10,12 +10,12 @@ class Mag2Cb;
 
 class AP_Compass_UAVCAN : public AP_Compass_Backend {
 public:
-    AP_Compass_UAVCAN(Compass &compass, AP_UAVCAN* ap_uavcan, uint8_t node_id, uint8_t sensor_id);
+    AP_Compass_UAVCAN(AP_UAVCAN* ap_uavcan, uint8_t node_id, uint8_t sensor_id);
 
     void        read(void) override;
 
     static void subscribe_msgs(AP_UAVCAN* ap_uavcan);
-    static AP_Compass_Backend* probe(Compass& _frontend);
+    static AP_Compass_Backend* probe();
 
     static void handle_magnetic_field(AP_UAVCAN* ap_uavcan, uint8_t node_id, const MagCb &cb);
     static void handle_magnetic_field_2(AP_UAVCAN* ap_uavcan, uint8_t node_id, const Mag2Cb &cb);